file photoDeFarra Gaymon.

NEWARK — DeFarra Gaymon spent a year planning his Montclair High School 30th reunion, making sure to block out the date well in advance of his busy schedule as president and CEO of a credit union in Atlanta.

Gaymon, 48, drove up to New Jersey Thursday for the gathering, which was to take place the following evening at the Crowne Plaza Hotel at the Meadowlands.

He would never make it.

Gaymon — whom everyone called "Dean" — was shot and killed Friday evening by an undercover detective from the Essex County Sheriff’s Office during a confrontation in Newark’s Branch Brook Park.

The detective, who went to the park at 6 p.m. after receiving complaints about people engaging in sexual activity in public, fired a single shot into Gaymon’s chest, authorities said.

Gaymon, married with four children, died at University Hospital in Newark at 9 p.m., said the Essex County Prosecutor’s Office, which is now investigating the shooting.

Gaymon’s death was the fifth law enforcement-related shooting in Newark in the past month and the ninth this year. There have been six fatal police-involved shootings in Newark in 2010, mirroring last year’s total through July, said Katherine Carter, a prosecutor’s office spokeswoman.

Gaymon was unarmed, though authorities said he "tussled" with the unidentified detective who was trying to arrest him on charges related to the original call.

Gaymon’s "life must have flashed before his eyes and he went into a panic," according to a law enforcement official with knowledge of the investigation, but who was not authorized to talk.

Authorities describe that section of Branch Brook Park — on West Drive near Bloomfield Avenue — as a known meeting point for sexual encounters. Sheriff’s officers have made more than 200 such arrests there in the last 18 months, all without incident.

"We’re saddened by this tragedy and our heartfelt condolences go out to his family," Essex County Sheriff Armando Fontoura said.

Gaymon’s sister, Kelly Gaymon Armstrong, said can’t believe her brother would ever challenge a police officer.

"There’s nothing threatening about his character," she said. "He’s a softie. It doesn’t add up."

Joyce Brogdon, a longtime friend who graduated from Montclair High a year after Gaymon, said, "nobody’s perfect, but he was the closest thing to perfection. He told me he was going to make VP by 40. He did. He was going be CEO. He was. He had the perfect life. He married his high school sweetheart."

Authorities said the detective is 29 years old and an eight-year veteran who has received several commendations. The detective, who was not injured, was taken to University Hospital after the shooting, where he was medicated, the prosecutor’s office said. He was "very traumatized" by what happened, Fontoura said.

The detective gave a statement to investigators Monday afternoon, Carter said, and more information was expected to be released today.

Gaymon lived with his wife, Melanie, and their four children in Suwanee, Ga., about 30 miles outside Atlanta. He graduated from Montclair High in 1980, then from Benedict College in Columbia, S.C., four years later, his sister said. He returned to New Jersey, where he became vice president of Summit Trust Company on Springfield Avenue in Summit, then moved back to South Carolina, where he became vice president for a credit union there. "He worked his way up," his sister said.

For the last four years, Gaymon has been president and CEO of Credit Union of Atlanta. Credit unions, which are owned and operated by their members, provide a variety of banking services. In a statement, Calvin Tucker, chairman of the company’s board of directors, said Gaymon "leaves a legacy which includes an unshakable commitment to the underserved, his staff and the credit union movement.